Ionic Switch Induced by a Rectangular-Hexagonal Phase Transition in Benzenammonium Columnar Liquid Crystals.

We demonstrate switching of ionic conductivities in wedge-shaped liquid-crystalline (LC) ammonium salts. A thermoreversible phase transition between the rectangular columnar (Colr) and hexagonal columnar (Colh) phases is used for the switch. The ionic conductivities in the Colh phase are about four orders of magnitude higher than those in the Colr phase. The switching behavior of conductivity can be ascribed to the structural change of assembled ionic channels. X-ray experiments reveal a highly ordered packing of the ions in the Colr phase, which prevents the ion transport

Surface Modification of Pseudoboehmite-Coated Aluminum Plates with Squaramic Acid Amphiphiles

[eng] The functionalization of interfaces has become very important for the protection or modification of metal (metal oxides) surfaces. The functionalization of aluminum is particularly interesting because of its relevance in fabricating components for electronic devices. In this work, the utilization of squaramic acids for the functionalization of aluminum substrates is reported for the first time. The physicochemical properties of the interfaces rendered by n-alkyl squaramic acids on aluminum metal substrates coated with pseudoboehmite [Al(O)x(OH)y] layers are characterized by contact angle, grazing-angle Fourier-transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and matrix-assisted laser desorption ionization time-of-flight. Moreover, we could confirm the squaramic functionalization of the substrates by diffuse reflectance UV−vis spectroscopy, which cannot be used for the characterization of UV−visinactive substrates such as carboxylates and phosphonates, commonly used for coating metallic surfaces. Remarkably, the results of sorption experiments indicate that long-chain alkyl squaramic acid desorbs from activated-aluminum substrates at a reduced rate compared to palmitic acid, a carboxylic acid frequently used for the functionalization of metal oxide surfaces. Theoretical calculations indicate that the improved anchoring properties of squaramic acids over carboxylates are probably due to the formation of additional hydrogen bonding interactions on the interface. Accordingly, we propose N-alkyl squaramic acids as new moieties for efficient functionalization of metal oxides

Crystallographic and Theoretical Evidence of Anion-π and Hydrogen‐Bonding Interactions in a Squaramide-Nitrate Salt

[eng] Synthetic anionic receptors are fundamental to the understanding of the mechanism of recognition phenomena, which is the basis of many fundamental biological processes. Recognition studies and X‐ray crystallography techniques provide accurate information on the structure of the molecular complexes and the nature of the interactions involved. Here, we present the first example of a squaramide-nitrate salt. X‐ray crystallography and theoretical studies show the important roles of anion-π and hydrogen‐bonding interactions in the crystal packing of this compound in relation to those found in the free squaramide solid structure

Effect of varying the composition and nanostructure of organic carbonate-containing lyotropic liquid crystal polymer electrolytes on their ionic conductivity

Nanostructured composite electrolyte films consisting of a cross-linked lyotropic liquid crystal (LLC) monomer, an organic carbonate liquid electrolyte (propylene carbonate, dimethylcarbonate, diethylcarbonate) and a Li salt (LiClO_4, LiBF_4, LiPF_6) were systematically prepared and characterized at two electrolyte concentrations (0.245 and 1.0 m) and four liquid loading levels (5, 15, 30, 50 wt %). The LLC morphology of the films was investigated using polarized light microscopy and powder X-ray diffraction; their ionic conductivity was investigated using AC impedance measurements. Higher liquid electrolyte loadings and Li salt concentrations generally increased ionic conductivity, regardless of the liquid electrolyte or salt used. Some mixed-phase LLC morphologies displayed good ionic conductivity; however, as initially prepared, these formulations were at the limit of liquid uptake. In contrast, composites with a type II bicontinuous cubic (QII) LLC phase containing ordered, three-dimensional interconnected nanopores exhibited good conductivity using much less liquid electrolyte and a lower Li salt concentration, indicating that this structure is more amenable to ion transport than less ordered/uniform morphologies. When wetted with electrolyte solution and integrated into Li/fluorinated carbon coin cells, the QII films were sufficiently strong to act as an ion-conductive separator and displayed stable open-circuit potentials. Many of the mixed-phase films gave shorted cells

Highly proton conductive phosphoric acid–nonionic surfactant lyotropic liquid crystalline mesophases and application in graphene optical modulators

Proton conducting gel electrolytes are very important components of clean energy devices. Phosphoric acid (PA, H3PO4·H2O) is one of the best proton conductors, but needs to be incorporated into some matrix for real device applications, such as into lyotropic liquid crystalline mesophases (LLCMs). Herein, we show that PA and nonionic surfactant (NS, C12H25(OCH2CH2)10OH, C12E10) molecules self-assemble into PANS–LLCMs and display high proton conductivity. The content of the PANS–LLCM can be as high 75% H3PO4·H2O and 25% 10-lauryl ether (C12H25(OCH2CH2)10OH, C12E10), and the mesophase follows the usual LLC trend, bicontinuous cubic (V1)–normal hexagonal (H1)–micelle cubic (I1), by increasing the PA concentration in the media. The PANS–LLCMs are stable under ambient conditions, as well as at high (up to 130 °C) and low (−100 °C) temperatures with a high proton conductivity, in the range of 10–2 to 10–6 S/cm. The mesophase becomes a mesostructured solid with decent proton conductivity below −100 °C. The mesophase can be used in many applications as a proton-conducting media as well as a phosphate source for the synthesis of various metal phosphates. As an application, we demonstrate a graphene-based optical modulator using supercapacitor structure formed by graphene electrodes and a PANS electrolyte. A PANS–LLC electrolyte-based supercapacitor enables efficient optical modulation of graphene electrodes over a range of wavelengths, from 500 nm to 2 μm, under ambient conditions